Biological Invasions of Cold-Water Coastal Ecosystems - Aquatic ...

Chapt 9C4. Peracaridan Crustaceans, page 9C4- 5
The species selected for the east to west geographical analysis of northern hemisphere
peracaridan NIS are common or abundant where they occur and documented either in the
literature or by personal observations. Species that are poorly documented, not examined
directly, cryptogenic, or that are not introduced across the North Atlantic or North Pacific, were
not included. For instance, the amphipod Chelicorophium curvispinum (Sars, 1895), which
spread from the Black and Caspian Sea to northern Europe (Eno et. al. 1997), and the introduced
mysid Acanthomysis bowmani Modlin and Orsi, 1997 in San Francisco Bay, which has unknown
origins, and many northern NIS that are native to the southern hemisphere are not in the scope of
this study and are therefore excluded from the analysis.
Long-term climate conditions in the northeast Pacific, including San Francisco Bay,
Puget Sound and Prince William Sound are inferred from monthly average climate time series
data for the Pacific Ocean and western Americas (Cayan et al. 1991). These data extend over
approximately 100 years up to 1986. Global records of sea surface temperature and precipitation
minus evaporation (http://www.cdc.noaa.gov/ 1998) are used for comparisons of temperature
among ocean regions. The term “western ocean” is used in reference to the Pacific Ocean
bordering the east Asian coast and the Atlantic Ocean bordering the eastern North American
coast. The term “eastern ocean” refers to the ocean areas bordering the west coasts of Europe
and North Africa and the west coast of North America.
Amphipods in Ballast Water
Ballast water samples were collected in vertical plankton tows from “dedicated” ballast
tanks, which are not contaminated by oil. Amphipods retained in the 0.25 mm mesh plankton
nets preserved in 5% formalin, subsequently transferred to 70% ethanol for final sorting and
identification. Samples were initially sorted under stereo microscopes at the Smithsonian
Environmental Research Center or at the field office in Port Valdez and final amphipod
identifications were performed at HMSC, Oregon State University.
The origins of the ballast water sampled (Table 9C4.3) were the Los Angeles-Long
Beach area, the San Francisco Bay area, Puget Sound (Anacortes) and the open ocean. One ship,
from the San Francisco Bay area, exchanged the ballast water at sea during transit. The potential
for dispersal of nonindigenous species is assessed from the presence of nonindigenous species in
samples.
Results
North - South Climate
The maximum, minimum, mean and range of monthly sea surface temperatures of the
eastern Pacific vary by 5 o C or less between 28 o and 52 o N (Figure 9C4.2). The 11 to 14 o C
maximum average monthly temperatures of Seward, Kodiak and Sitka, Alaska (between 58 and
60 o N) overlap the Neah Bay, Washington maximum surface temperatures at 48 o N and are
similar to the 13 o C average sea surface temperatures adjacent to San Francisco at 38 o N (Figure
2). Nonindigenous species expected to reach south central Alaska might include those that can
reproduce within Puget Sound in summer or in average San Francisco temperatures (Figure
9C4.2).